This application claims the benefit of Korean Patent Application No. 2000-85271, filed on Dec. 29, 2000.
1. Field of the Invention
This invention relates to a liquid crystal display, and more particularly to a method of driving a liquid crystal display that is adaptive for improving uniformity in a driving method employing multiplexors of the liquid crystal display.
2. Description of the Related Art
Generally, a liquid crystal display (LCD) uses a pixel matrix arranged in each intersection between gate lines and data lines to thereby display a picture corresponding to a video signal, such as a television signal. Each pixel consists of a liquid crystal cell controlling a quantity of transmitted light in accordance with a data signal, and a thin film transistor (TFT) for switching the data signal to be applied from the data line to the liquid crystal cell. The pixel matrix is positioned between two glass substrates. The LCD includes driving integrated circuits for driving gate lines and data lines.
In the conventional LCD, a driving integrated circuit for driving the data lines applies signals to the data lines using six multiplexors.
FIG. 1 is a block diagram showing a configuration of a conventional data driving integrated circuit for driving a liquid crystal display panel, which includes a multiplexor block 2 connected between a data driver 1 and a liquid crystal display panel 3.
Outputs DL1 to DLn from the data driver 1 are applied to the multiplexor block 2. The multiplexor block 2 multiplexes an applied signal using six multiplexors (MUX""s) to sequentially apply the same to the data lines of the liquid crystal display panel 3.
Referring to FIG. 2, the multiplexor block 2 consists of six multiplexors connected to each output DL1 to DLn of the data driver 1. The output DL1 to DLn of the data driver 1 is applied to a source terminal of each multiplexor (MUX) while a gate pulse as shown in FIG. 3 is sequentially applied to a gate terminal of each MUX to thereby turn on the MUX""s. Thus, a data signal is stored in a capacitor of the data line via a drain terminal of each MUX. Then, a data signal is charged in a pixel electrode (not shown) just until the gate pulse goes off.
FIG. 3 shows a xe2x80x9cturned-onxe2x80x9d sequence of six MUX""s for applying a gate pulse.
Referring to FIG. 3, data with a first color is supplied to the first liquid crystal cell, one of the first and second liquid crystal cells, and then data with the first color is supplied to the second liquid crystal cell. The first color for the first liquid crystal cell is adjacent to the first color for the second liquid crystal cell, as shown in the first line of FIG. 3. Data with a second color is supplied to the fourth liquid crystal cell of the third and fourth liquid crystal cells and then is supplied to the third liquid crystal cell. Data with a third color is supplied to the fifth liquid crystal cell of the fifth and sixth liquid crystal cells and then is supplied to the sixth liquid crystal cell. Herein, the first color is a red; the second color is a green; and the third color is a blue. In this manner, the MUX""s are sequentially turned on to supply data to each liquid crystal cell of the data lines.
Upon driving of the MUX""s, a data signal is stored in a capacitor of the data line when a gate pulse is applied to each MUX, while a data signal is charged in the pixel electrode just until the gate pulse turns off. Thus, a voltage difference is generated when the data signal is applied from the data line of the liquid crystal display panel 3 and then is charged in the pixel electrode. The voltage difference between the data lines 3 caused by a charge characteristic difference as shown in FIG. 4.
As can be seen from FIG. 4, a voltage difference as indicated by dotted lines in the figure is generated from voltage waveforms of Data1 to Data6 at a time from turning-on of the gate pulse until turning-off of the gate pulse, that is, at a sampling time. Also, a voltage difference is generated between the data lines due to a leakage current as shown in FIG. 5.
As can be seen from FIG. 5, a voltage difference, as indicated by dotted lines in the figure is generated from voltage waveforms of Data1 to Data6 at a time from turning-on of the gate pulse until turning-off of the gate pulse, that is, at a sampling time. Accordingly, in a six-multiplexor driving scheme, red (R) is applied in MUX1 and MUX2 intervals; green (G) is applied in MUX3 and MUX4 intervals; and blue (G) is applied in MUX5 and MUX6 intervals, to prevent stripe generation caused by coupling between the data lines upon application of data.
Normal-temperature operation of the LCD does not cause stripe generation. However, low-temperature operation or a mobility deterioration of the liquid crystal allows a stripe shape to be generated in the liquid crystal display panel because a charge characteristic difference between the multiplexors exists. Particularly, charge time at the MUX5 and MUX6 is shortest. Moreover, a large leakage current causes problems such as poor picture quality, because the charge time (MUX turn_on through Gate_off), during which a voltage of the data line is charged via the multiplexors, should be held is different depending on which MUX is charged, that is, which MUX number. As a result, a minute voltage difference caused by poor quality of line shape is generated such that it can be easily perceived by a human""s eye.
Accordingly, it is an object of the present invention to provide a method of driving a liquid crystal display that is adaptive for improving uniformity in a driving method employing multiplexors of the liquid crystal display.
In order to achieve these and other objects of the invention, a method of driving a liquid crystal display according to an embodiment of the present invention includes the steps of sequentially applying a gate driving signal to gate lines for a sequential scanning for each line; supplying data to liquid crystal cells with the same color being adjacent to each other in a scanning interval of a first scanning line; and differentiating an application sequence of data to the liquid crystal cells with the same color being adjacent to each other in a scanning interval of a second scanning line from that in a scanning interval of the first scanning line.
The driving method further includes the steps of, at the first line, supplying data to the first liquid crystal cell of the first and second liquid crystal cells with a first color being adjacent to each other and thereafter supplying the data to the second liquid crystal cell; supplying data to the fourth liquid crystal cell of the third and fourth liquid crystal cells with a second color and thereafter supplying the data to the third liquid crystal cell; and supplying data to the fifth liquid crystal cell of the fifth and sixth liquid crystal cells with a third color and thereafter supplying the data to the sixth liquid crystal cell. Herein, first color is a red, a second color is a green, and a third color is a blue.
The driving method further includes the steps of, at the second line, supplying data to the second liquid crystal cell and thereafter supplying the data to the first liquid crystal cell; supplying data to the third liquid crystal cell and thereafter supplying the data to the fourth liquid crystal cell; and supplying data to the sixth liquid crystal cell and thereafter supplying the data to the fifth liquid crystal cell.
A method of driving a liquid crystal display according to another embodiment of the present invention includes the steps of sequentially applying a gate driving signal to gate lines every frame for a sequential scanning for each frame; supplying data to liquid crystal cells with the same color being adjacent to each other in a specific sequence at a first frame of said frames; differentiating an application sequence of data to the liquid crystal cells with the same color being adjacent to each other at a second frame following the first frame from that that at the first frame; equalizing data application sequence at a third frame following the second frame to that at the second frame; equalizing data application sequence at a fourth frame following the third frame to that at the first frame; and periodically repeating data application in said sequences at the first to fourth frames.
The driving method further includes the steps of, at the first frame, supplying data to the first liquid crystal cell of the first and second liquid crystal cells with a first color being adjacent to each other and thereafter supplying the data to the second liquid crystal cell; supplying data to the fourth liquid crystal cell of the third and fourth liquid crystal cells with a second color and thereafter supplying the data to the third liquid crystal cell; and supplying data to the fifth liquid crystal cell of the fifth and sixth liquid crystal cells with a third color and thereafter supplying the data to the sixth liquid crystal cell. Herein, the first color is a red, a second color is a green, and a third color is a blue.
The driving method further includes the steps of, at the second frame, supplying data to the second liquid crystal cell and thereafter supplying the data to the first liquid crystal cell; supplying data to the third liquid crystal cell and thereafter supplying the data to the fourth liquid crystal cell; and supplying data to the sixth liquid crystal cell and thereafter supplying the data to the fifth liquid crystal cell.